Flash memory is a type of long-term non-volatile storage device that does not require power to retain data, and has advantages of high integration, fast access speed and easiness to erase and rewrite. Therefore, flash memory has become the mainstream of non-volatile memory. Depending on the structure, the flash memory can be divided into two types: NOR flash memory and NAND flash memory. Compared to the NOR flash memory, the NAND flash memory can provide higher cell density, higher storage density, and faster access speed.
With the development of planar flash memory, semiconductor manufacturing process has made great progress. However, the current development of the planar flash memory has faced various challenges: physical limits, such as exposure technology limit, development technology limit, and storage electronics density limit, etc. Under this situation, a three-dimensional (3D) flash memory, such as a 3D NAND flash memory, is proposed to address the difficulties encountered in the planar flash memory and to further lower production cost of unit memory cell.
However, the conventional methods for forming a semiconductor device including the 3D NAND flash memory cells are complicated and with high cost. The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems in the art.